CN112553561B

CN112553561B - Method for preparing nitride enhanced wear-resistant coating by thermal spraying

Info

Publication number: CN112553561B
Application number: CN202011437971.4A
Authority: CN
Inventors: 马煜林; 张瑜; 代鹏宇; 杨彦哲; 张惠杰; 杨昌迪; 匡成阳
Original assignee: Shenyang University
Current assignee: Shenyang University
Priority date: 2020-12-11
Filing date: 2020-12-11
Publication date: 2023-01-24
Anticipated expiration: 2040-12-11
Also published as: CN112553561A

Abstract

The invention provides a method for preparing a nitride enhanced wear-resistant coating by thermal spraying, which comprises the following steps: step 1, taking ferroboron powder with the granularity of 0.5-5 mu m and ferrovanadium nitride powder as spraying raw materials, and step 2, soaking the raw material powder into ethanol, and then placing the raw material powder into a rod mill for mixing for 2-5 min per gram of the raw material powder; step 3, placing the powder mixed in the step 2 into spraying equipment, and spraying a material to be sprayed; and 4, carrying out surface heat treatment on the sprayed coating to strengthen the bonding degree of the coating. The invention takes ferroboron and ferrovanadium nitride as spraying raw materials, removes the high-temperature sintering step for preparing spraying powder, shortens the process flow, reduces the production cost, and simultaneously, the prepared wear-resistant coating has good effect.

Description

Method for preparing nitride enhanced wear-resistant coating by thermal spraying

Technical Field

The invention relates to the technical field of coating preparation, in particular to a method for preparing a nitride enhanced wear-resistant coating by thermal spraying.

Background

The wear-resistant coating generally means a coating in which a release coating having a friction resistance or a coating containing ceramic particles having a high wear resistance is applied to the surface of a substrate, wherein the amount of the ceramic particles in the coating is such that there are at least 3 particles per 1 cm-long cross section of the coating. The wear-resistant material is coated on the surface of the equipment component to protect the base material of the equipment component in order to reduce the wear of the equipment component caused by the erosion of materials. The wear-resistant coating can be generally divided into a chemically bonded wear-resistant coating and a thermally sprayed wear-resistant coating according to the forming process. The patent adopts a thermal spraying wear-resistant coating method, namely plasma spraying is adopted to spray on the surface of metal to form boron nitride and vanadium nitride ceramic hard wear-resistant particles, so as to achieve the purpose of improving the surface wear resistance.

At present, a lot of patents exist for preparing wear-resistant coatings and nitride powder by thermal spraying, and a patent 200810046930.5 (application number) provides a preparation method of flying saucer-shaped nanometer hexagonal boron nitride powder, wherein the boron nitride powder is obtained by carrying out heat treatment on boric acid or a compound of diboron trioxide and nitrogen; patent 201080040377.X discloses a thermal spraying powder, which is prepared by sintering tungsten carbide or chromium carbide and iron-based alloy to form granular spraying powder; patent 201610286598.4 relates to a zirconium boride plasma spraying raw material and a preparation method thereof, wherein zirconium boride powder and boron carbide are mixed and sintered at high temperature to prepare the spraying raw material; patent 201480005501.7 discloses a method for preparing chromium nitride-containing spray powder, wherein chromium nitride is mixed with nickel, cobalt and iron alloy and sintered to prepare a spray raw material; patent 201910716226.4 provides a method for spraying a plasma wear-resistant layer, wherein a surface to be sprayed is preheated, a nickel-phosphorus alloy layer is prepared by spraying twice, and then the coating is subjected to heat treatment.

The invention adopts cheap ferroboron and ferrovanadium nitride as raw materials, removes the step of high-temperature sintering, and can form the coating of boron nitride and vanadium nitride on the surface by one-time spraying.

Disclosure of Invention

The invention aims to provide a method for preparing a nitride enhanced wear-resistant coating by thermal spraying, which can effectively improve the hardness and the wear resistance of the surface of an iron-based alloy workpiece and simultaneously reduce the production cost compared with other spraying processes.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for preparing a nitride enhanced wear-resistant coating by thermal spraying comprises the following steps:

step 1, ferroboron powder with the granularity of 0.5-5 mu m and ferrovanadium nitride powder are used as spraying raw materials, and the mass ratio of the ferroboron powder to the ferrovanadium nitride powder in the raw materials is (3-5) to 1;

step 2, soaking the raw material powder into ethanol, and then placing the raw material powder into a rod mill for mixing for 2-5 min per gram of the raw material powder;

step 3, placing the powder mixed in the step 2 into spraying equipment, spraying a material to be sprayed, wherein argon and nitrogen are used as plasma gases in the spraying process, the mass ratio of the nitrogen is 10-25%, the flow rate of the plasma gases is 4000-6000L/h, the plasma pressure is 3.0-6.0 MPa, the current is adjusted to 700-900A, the arc temperature is controlled to be 3500-5000 ℃, and the powder feeding amount is 0.4-1.0 g/min;

and 4, carrying out surface heat treatment on the sprayed coating to strengthen the bonding degree of the coating, wherein the heat treatment conditions are as follows: controlling the surface temperature to be 700-1100 ℃, and keeping the temperature for 4-8 h.

Further, in the ferroboron alloy in the step 1, the content of boron is 45.0-55.0%, the content of carbon is less than 0.1%, the content of niobium is less than 0.01%, the content of aluminum is less than 0.01%, the content of titanium is less than 0.01%, the content of sulfur is less than 0.01%, the content of phosphorus is less than 0.01%, the content of impurities is less than 0.01%, and the balance is iron; the vanadium content in the vanadium nitride ferrovanadium is 25.0-35.0%, the nitrogen content is 15.0-35.0%, the impurity content is less than 0.1%, and the balance is iron.

Further, in the step 1, the content of boron in the ferroboron alloy is preferably 52%; the vanadium content in the vanadium iron nitride is 32 percent, and the nitrogen content is 30 percent; the particle size of the ferroboron and ferrovanadium nitride powder is 1-2 μm; the mass ratio of the ferroboron alloy to the ferrovanadium nitride powder in the raw materials is 4.2.

Furthermore, the volume ratio of the ethanol to the raw material powder in the step 2 is (10-20): 1, and the ethanol is an analytical reagent.

Further, in the step 2, the rotating speed of the rod mill is 10-20 r/min, and the filling rate is 30-45%.

Furthermore, in the step 3, powder is supplied to the spray gun through a powder feeder during spraying, and argon is used as powder feeding gas.

Further, the material to be sprayed in the step 3 is ferroalloy, before spraying, the area to be sprayed of the material to be sprayed needs to be subjected to surface cleaning and derusting treatment, a high-pressure air gun is used for sand blasting to reinforce the area to be sprayed, the air pressure is 15-25 MPa, and the sand blasting is performed by using quartz sand with purity of more than 98%.

Further, after the spraying in step 3, the thickness of the coating is 200 to 500 μm, preferably 450 μm.

Further, the heat treatment condition in step 4 is preferably a surface temperature of 950 ℃.

The invention adopts a thermal spraying method to prepare the wear-resistant coating, namely plasma spraying equipment is adopted, ferroboron and ferrovanadium nitride are used as raw materials, and boron nitride and vanadium nitride ceramic hard wear-resistant particles are formed on the surface of metal, so that the aim of improving the surface wear resistance is fulfilled. The ferroboron and the ferrovanadium nitride are used as spraying raw materials, so that the high-temperature sintering step for preparing spraying powder is eliminated, the process flow is shortened, the production cost is reduced, and the prepared wear-resistant coating has good effect.

The invention has the advantages and beneficial effects that:

1. according to the invention, ferroboron and ferrovanadium nitride are selected as spraying raw materials, so that the raw material cost is reduced compared with other patent methods of the same type;

2. the invention removes the high-temperature sintering step of the raw material powder, shortens the process flow and reduces the production cost;

3. the method for preparing the nitride enhanced wear-resistant coating by thermal spraying can better improve the wear resistance of the metal surface.

Drawings

FIG. 1 is a coating topology prepared in example 1;

FIG. 2 is a coating topology prepared in example 2;

FIG. 3 is the coating profile prepared in example 3.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

The invention provides a method for preparing a nitride enhanced wear-resistant coating by thermal spraying, which comprises the following steps:

firstly, selecting ferroboron and ferrovanadium nitride, wherein the ferroboron comprises 46.5% of boron, 0.08% of carbon, 0.005% of niobium, 0.006% of aluminum, 0.002% of titanium, less than 0.01% of sulfur, less than 0.01% of phosphorus, less than 0.01% of impurities and the balance of iron by mass fraction; the vanadium content in the vanadium nitride ferrovanadium is 27.2 percent, the nitrogen content is 16.8 percent, the impurity content is less than 0.1 percent, and the rest is iron; respectively spray-drying the ferroboron and ferrovanadium nitride, respectively crushing and ball-milling the ferroboron and ferrovanadium nitride into powder, and screening ferroboron and ferrovanadium nitride powder with the granularity of 0.5-3 mu m as spraying raw materials, wherein the mass ratio of ferroboron powder to ferrovanadium nitride powder in the raw materials is 3.2;

secondly, the material to be sprayed is ferroalloy, the surface of the area to be sprayed is cleaned and derusted, a high-pressure air gun is used for blasting sand to reinforce the area to be sprayed, the air pressure is 16MPa, and the sand blasting is carried out by using quartz sand with purity of more than 98%;

thirdly, immersing the raw material powder into ethanol (analytically pure) and mixing the raw material powder by a rod mill, wherein the volume ratio of the ethanol to the raw material powder is 13; selecting a low-rotation-speed rod mill, wherein the rotation speed is 12r/min, and the filling rate is 36%; mixing for 2min per gram of raw material powder;

fourthly, placing the mixed powder into spraying equipment, and selecting argon and nitrogen as plasma gas, wherein the mass ratio of the nitrogen is 14%, the flow rate of the plasma gas is 4200L/h, the pressure of the plasma gas is 3.3MPa, the current is adjusted to 750A, and the temperature of an electric arc is controlled to 4200 ℃; supplying the mixed powder to a spray gun through a powder feeder, and feeding the powder by argon gas, wherein the powder feeding amount is 0.4g/min;

fifthly, after spraying the spraying area, the thickness of the coating is 250 microns, the surface heat treatment is carried out to enhance the bonding degree of the coating, the surface temperature reaches 780 ℃, and the coating is taken out after heat preservation is carried out for 8 hours.

Example 2

firstly, selecting a ferroboron alloy and ferrovanadium nitride, wherein the ferroboron alloy contains 53.2% of boron, 0.09% of carbon, 0.004% of niobium, 0.002% of aluminum, 0.002% of titanium, less than 0.01% of sulfur, less than 0.01% of phosphorus, less than 0.01% of impurities and the balance of iron by mass fraction; the vanadium content in the vanadium nitride ferrovanadium is 32 percent, the nitrogen content is 30 percent, the impurity content is less than 0.1 percent, and the rest is iron; respectively spray-drying the ferroboron and ferrovanadium nitride, respectively crushing and ball-milling the ferroboron and ferrovanadium nitride into powder, and screening ferroboron and ferrovanadium nitride powder with the particle size of 2-5 mu m as spraying raw materials, wherein the mass ratio of ferroboron powder to ferrovanadium nitride powder in the raw materials is 4.2;

secondly, the material to be sprayed is ferroalloy, the surface of the area to be sprayed is cleaned and derusted, a high-pressure air gun is used for blasting sand to reinforce the area to be sprayed, the air pressure is 24MPa, and the sand blasting is carried out by using quartz sand with purity of more than 98%;

thirdly, immersing the raw material powder into ethanol (analytically pure) and mixing the raw material powder by a rod mill, wherein the volume ratio of the ethanol to the raw material powder is 18; selecting a low-rotation-speed rod mill, wherein the rotation speed is 17r/min, and the filling rate is 42%; mixing for 5min per gram of raw material powder;

fourthly, placing the mixed powder into spraying equipment, selecting argon and nitrogen as plasma gas, wherein the mass ratio of the nitrogen is 23%, the flow rate of the plasma gas is 5800L/h, the pressure of the plasma gas is 5.5MPa, and the current is adjusted to 880A, so that the temperature of the electric arc is controlled to 4800 ℃; feeding the mixed powder to a spray gun through a powder feeder by adopting argon gas, wherein the powder feeding amount is 0.95g/min;

fifthly, after spraying of the spraying area, the thickness of the coating is 450 microns, the combination degree of the coating is strengthened through surface heat treatment, the surface temperature reaches 1050 ℃, and the coating is taken out after heat preservation for 4 hours.

Example 3

firstly, selecting ferroboron and ferrovanadium nitride, wherein the ferroboron comprises 52.0% of boron, 0.08% of carbon, 0.006% of niobium, 0.003% of aluminum, 0.007% of titanium, less than 0.01% of sulfur, less than 0.01% of phosphorus, less than 0.01% of impurities and the balance of iron by mass fraction; the vanadium content in the vanadium nitride ferrovanadium is 30.2 percent, the nitrogen content is 26.2 percent, the impurity content is less than 0.1 percent, and the rest is iron; respectively spray-drying the ferroboron and ferrovanadium nitride, respectively crushing and ball-milling the ferroboron and ferrovanadium nitride into powder, and screening ferroboron and ferrovanadium nitride powder with the particle size of 1-2 mu m as spraying raw materials, wherein the mass ratio of ferroboron powder to ferrovanadium nitride powder in the raw materials is 5;

secondly, the material to be sprayed is ferroalloy, the area to be sprayed is subjected to surface cleaning and rust removal treatment, a high-pressure air gun is used for blasting sand, the area to be sprayed is subjected to strengthening treatment, the air pressure is 21MPa, and the blasting sand adopts quartz sand with purity of more than 98%;

thirdly, immersing the raw material powder into ethanol (analytically pure) and mixing by a rod mill, wherein the volume ratio of the ethanol to the raw material powder is 15; selecting a low-rotation-speed rod mill, wherein the rotation speed is 14r/min, and the filling rate is 40%; mixing for 3min per gram of raw material powder;

fourthly, placing the mixed powder into spraying equipment, and selecting argon and nitrogen as plasma gas, wherein the mass ratio of the nitrogen is 18%, the flow rate of the plasma gas is 5200L/h, the pressure of the plasma gas is 4.5MPa, the current is adjusted to 800A, and the arc temperature is controlled to be 4200 ℃; feeding the mixed powder to a spray gun through a powder feeder by adopting argon gas, wherein the powder feeding amount is 0.75g/min;

fifthly, after spraying of the spraying area, the thickness of the coating is 350 microns, the combination degree of the coating is strengthened through surface heat treatment, the surface temperature reaches 950 ℃, and the coating is taken out after heat preservation for 6 hours.

The appearances of the coatings prepared in the embodiments 1, 2 and 3 are shown in fig. 1, 2 and 3, in the preparation process, the ferroboron alloy and the ferrovanadium nitride are heated and melted to form a layered coating attached to the surface of the matrix, and the boron nitride and the vanadium nitride ceramic hard wear-resistant particles are distributed in the coating, so that the matrix has wear-resistant characteristics.

The technical idea of the present invention is described in the above technical solutions, and the protection scope of the present invention is not limited thereto, and any changes and modifications made to the above technical solutions according to the technical essence of the present invention belong to the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing a nitride enhanced wear-resistant coating by thermal spraying is characterized by comprising the following steps:

step 1, using ferroboron powder and ferrovanadium nitride powder with the granularity of 0.5-5 mu m as spraying raw materials, wherein the mass ratio of the ferroboron powder to the ferrovanadium nitride powder in the raw materials is (3-5) to 1; the boron-iron alloy comprises, by mass, 45.0-55.0% of boron, less than 0.1% of carbon, less than 0.01% of niobium, less than 0.01% of aluminum, less than 0.01% of titanium, less than 0.01% of sulfur, less than 0.01% of phosphorus, less than 0.01% of impurities and the balance of iron;

step 2, soaking the raw material powder into ethanol, and then placing the raw material powder into a rod mill for mixing for 2-5 min per gram of raw material powder;

step 3, placing the powder mixed in the step 2 into spraying equipment, spraying a material to be sprayed, wherein argon and nitrogen are used as plasma gas in the spraying process, the mass ratio of the nitrogen is 10-25%, the flow rate of the plasma gas is 4000-6000L/h, the plasma gas pressure is 3.0-6.0 MPa, the current is adjusted to 700-900A, the arc temperature is controlled to be 3500-5000 ℃, and the powder feeding amount is 0.4-1.0 g/min;

2. The method for preparing the nitride reinforced wear-resistant coating by thermal spraying according to claim 1, wherein in the step 1, the vanadium content is 25.0-35.0%, the nitrogen content is 15.0-35.0%, the impurity content is less than 0.1%, and the balance is iron by mass fraction.

3. The method for preparing the nitride reinforced wear-resistant coating by thermal spraying according to claim 1, wherein the volume ratio of ethanol to the raw material powder in the step 2 is (10-20): 1, and the ethanol is an analytical reagent.

4. The method for preparing the nitride reinforced wear-resistant coating by thermal spraying according to claim 1, wherein the rotation speed of the rod mill in the step 2 is 10-20 r/min, and the filling rate is 30% -45%.

5. The method for preparing the nitride reinforced wear-resistant coating by thermal spraying according to claim 1, wherein powder is supplied to a spray gun by a powder feeder during the step 3, and argon is used as a powder feeding gas.

6. The method for preparing the nitride reinforced wear-resistant coating by thermal spraying according to claim 1, wherein the material to be sprayed in the step 3 is ferroalloy, the area to be sprayed of the material to be sprayed is subjected to surface cleaning and rust removal treatment before spraying, a high-pressure air gun is used for carrying out sand blasting on the area to be sprayed, the air pressure is 15-25 MPa, and the sand blasting is carried out by using quartz sand with purity of more than 98%.

7. The method for preparing the nitride reinforced wear-resistant coating by thermal spraying according to claim 1, wherein the thickness of the coating after the spraying in the step 3 is 200-500 μm.